Heterodyne receiving apparatus



March 3, 1931. H. CHIREIX HETERODYNE RECEIVING APPARATUS Filed March 27, 1926 LOCAL o o- HIG H FREQ U ENCY OSCILLATOR)- O LOW FREQUENCY AMPLIFIER AMPL-(FIER- a LOCAL c 4 05c! LLATO 0- LOW FREQUENCY AMPLIFIER.

O 0- HlGH FREQUENCY Z AMPLIFlER c LOCAL OSCILLATOR FREOUZENCY CHANGER To MOTOR. ELEMENT Ears lNVENTOR HENRI CHI REIX TTORNEY Fatented Mar. 3, 1931 UNITED. STATES pm' orries HENRI cnmnrx, orrAnrs, manner;

I HETERODYNE RECEIVING Arrnrtartrs Application filed March 27, 1926, Serial No. 97,876, and in 'Fran'ce August 21, 1925.

The present invention has as its object the construction of a', receiver for wireless telegraphy and telephony of a new.:type.

Receiving apparatus are already known of the kind whereinthe frequency of the incommg waves'is lowered by means of a change in frequency, with the end in view of amplifying theminore readily, reducing the number of controls, and attaining sharper tuning. In all of'the receivers of this type, the change in frequency is brought about by the aid of vacuum tubes, while tuning is accomplished by the'aid of tuned electrical circuits.

The present invention consists in utilizing for the two operations, i. e., changing the frequency and tuning, one and the same element or means, namely, amotor, or moving, element acting upon a piece of piezo-electric quartz, or other substances, possessing piezoelectric properties. The motor element may consist, for example, of a condenser, one plate or armature of which is stationary, while the other one is afiixed to the crystal.- Again, there may be employed as a motor element an electromagnet whose mobile armature is affixed to the said crystal. The other plate of the crystal in either case, is rendered station ary or immobile by any convenient means.

If the sum of two high frequency potentials is applied to a condenser or to an electromagnet, the force of attraction naturally will be of a complex nature. Calculation shows that by resolving this force into a Fourier series, there is found, among others, a frequency component which is equal to the sum of the frequencies, and another component of frequency-equal to the difierence of the frequencies. If then,this force is applied to a piezoelectric piece of quartz, and if the frequency of one of said potentials be varied, the said piece of quartz will be subjected to vibration-s of great amplitude whenever the total or the difference of the exciting frequencies coincides with its natural period (or with one of its harmonics). This vibration of the quartz may be impressed upon a pair of electrodes, and there will be procured, as a result, a wave having a frequency similar to the natural period of the piece of quartz, or to one of its harmonics. If one of the two frequencies applied to the motor driving element is modulated by Morse signals, or by speech, the vibration-of the quartz will follow or respond to such modulation, provided that the damp.

ing is sufiicient and the wave developed at the electrodes of the quartz itself will be modulated similarly to the former. Since the resonance curve of the quartz is very sharp, it will generally be necessary to provide for damping," or to give it a natural period sufficiently high whenever speech transmission is con.- cerned; in this case, it will usually be preferable to provide for a raising of the frequency. Y

fier-detector connected across the electrodes of the quartz, and characterized by optimum operation at the natural frequency of the quartz. r

' It must be noted that the piezo-electric quartz thus used actually functions as a motor-generator receiving two frequencies at the motor end, and delivering a single frequency of invariable value at the generating end. It can thus be said that the connection between the elements preceding the piezoelectric quartz and those following it is a purely mechanical connection. In view of the character of this connection and the exceptionally high tuning properties of the quartz, the disturbance-precluding properties of the scheme are very marked.

The invention is shown by way of example in the accompanying drawing in which,

Fig. 1 is a diagrammatic arrangement according to the invention in which a condenser is used as the motor element of the piezo electricorystal,

Fig. 2 is a modification ofthe arrangement shown in Fig. 1 in which an electromagnetic motor element is used,

Fig. 2a is a modification of the motor. element shown inFig. 1,

quartz armatures or plates being connected with the amplifier-detector 7 j-oinedto'telephone 8.

:Referringmore specifically 'to Fig. 1, elementfi consists of 'two fixed metallic armatures a and b, 'and a mobile metallic armature 0 which movable conjointly with the quartz. The laminaof quartz (Z is cemented t-o tlie'armaturesa and c, and therefore'armaturec willzbeset into vibrations as the*quartz'vibrates.

Referringto 2, wheretthe structure up tothe motor element corresponds to Fig. 11,

inotor element Gconsistsofa laminated fixed core (2 made of'magn'etic material, and carryinga winding [25,:aunobileimagnetic armature a affixed, as by cementation, to the quartz lamina vbl, :and a ffizxed :arm'ature a" cemented, also, to'the quartz lamina (Z. WVhen'the' quartz vibrates, armature .0 will he set in motion conj ointly with i it.

With out departing :from :the spirit of the invention which =co'nsis'ts essentially in im partinga resonant vibration toa:piezo-'electrio crystal under the combined action 0f two lu h-frequency waves with: a =-.view1toobtaining a selective change in frequency, it is,- of course, :possible to conceive other modifications, especially as regards the mode of action on the qu. rtz. For instance,-it would be .possible to'set the quartz in vibratio'n by means-Of two pairs of electrodes to which the two high frequency waves areapplied.

Thus,as shown in Fig.2a, it'being understood the structure preceding and following the motor element is the same asin Fig. '1, the quartz lamina (Z is cemented between the plates 0 and a *while the pairofele'ctrod'es b'", 6 correspond 'to the single condenser electrode bin Fig. 1. I

,It should be understood that while the above described arrangement is the preferred one it is=quite feasible'to use apiezo-electric resonator to increase the. sharpness of tuning after a change in frequencybyjany of the well known methods. 7

In the case of such an arrangement, as will be readily understood, the'quartz or crystal does not participate in the frequencymhanging phenomena, and its use'se'rves the sole purpose of imparting 'an exceptionally marked selectivity to the-amplifierarrangement mounted next to the frequency changing means.

This particular modification of the invention is illustrated by way of example in Fig. 3 where the same numerals are used for denoting the same elements or parts as in Figs. Land 2. :It will he noted that the localoscillator, instead of acting directly upon the .circuit containing the piezo-electric motor 7 element, acts on one of the preceding circuits.

"(lnthe'example*here chosen the oscillator 4.

is coupled, asat 5, to the antenna-ground circuit, 1'). The output from the frequency changer-2, whiclrinoludes the high frequency amplifier shown in Figs. 1 and 2, is coupled, as at Bjto the motor elementtias in Fig. 1, or tothe elementmas'in Fig. 2. Themotor element assemblythus happensto'be-simply a part of the amplifieredetector "7 whose function is to: amplify and render perceptible the signals whose frequency has-been previously altered.

.The use of piezo-electric resonators nor timed circuitsof the 'kind here inquestion can beextended to cover all other types of receivers'than those h'ereinbefore mentioned; in .particularit'willbe of advantage whenever thepoint is to increasethe sharpness of tuning after'achange in frequency.

l laving described my invention, I clann:

"1.1L high frequency signalling circuit, comprising means responsive to incoming signa ,a motor member-e connected with said means and-includinga movable element, and api'ezo el'ectri'c crystal mounted upon said FJOVilJlG element for changing the frequency of theincomingsignals.

A high frequency signalling circuit, comprising nneans responsive to incoming signals, alloca'l oscillator, a motor :member connected to the oscillator and responsive means, the .motor member including a movable "element adapted to be. vibrated by the combined oscillations ofthe local oscillator and the :incoming signals, and a piezo-electrio crystabmounted upon said movable element.

o. A liigh frequency signalling circuit, comprising, in combination, means for receiving signal oscillations, a capacitive motor elen'ie'nt including a movable plate, a piezoelectric crystal mechanically coupled to said plate,.and a local oscillation generator having a 'frequency equaltothe difference of the -'signal frequency and the natural frequency of the -piezo electric crystal, the motor element beingconnected to'thefgenerator and re'cei-VingTmeans.

4. A high frequency signalling circuit, comprising, in combination, means for 11'6- cei'ving signal oscillations, 1 a 'mo'tor nie'mber including a movable plate connected -to the receiving :means, a piezo-electric' crystal me-f chanically afiixed to said plate, and adocal oscillation r genera'tor connected to the: motor Tit member having a frequency equal to the sum of the signal frequency and the natural frequency of thepiezo-electric crystal, the combined signal and local oscillations acting upon said motor member.

5. A high frequency signalling circuit, comprising means for receiving signalling energy, a local oscillator, a capacitive motor memberincluding a movable element, means responsive to the received energy and the local energy for energizing said movable element, a piezo-electric crystal mechanically mounted upon the movable element, and signal responsive means connected to said crystal.

6. A high frequency signalling circuit, comprising means responsive to incoming oscillations, a local oscillator, a capacitive motor element including amovable plate, means responsive to the resultant beat frequency between incoming and local oscillations for electrostatically energizing said movable plate, a piezo-electric crystal, having a natural frequency equal to saidbeat fre-- quency, mounted upon the movable plate, and signal responsive means connected to said crystal. 7

7. A heterodyne receiving system having a circuit for combining incoming and local oscillations, a condenser motor element in-- cluding a movable plate connected to said circuit, a piezo-electric crystal mechanically mounted upon said movable plate, and signal responsive means connected With the crystal.

8. A heterodyne receiving system, comprising means responsive to incoming oscillations, a source of local oscillations, means including a condenser for combining the incoming and local oscillations to produce a beatfrequency, said condenser having a fixed plate and a movable plate, a piezo electric crystal mounted on said movable plate, a second fixed plate mounted on the crystal, and electrical indicating means connected to the movable plate and to said second fixed plate.

9. A receiving system, comprising means responsive to incoming oscillations, a source of local oscillations, a motor means responsive to the beat frequency produced by superposing the incoming and local oscillations, said motor means including a fixed plate and a movable plate, a piezo-electric crystal mounted on said movable plate, a second fixed plate mounted onthe crystal, and electrical indicating means connected to the movable equal to said beat frequency.

HENRI CHIREIX. 

